/Engine/Source/Runtime/Landscape/Public/LandscapeDataAccess.h
void GetLocalTangentVectors ( int32 LocalX, int32 LocalY, FVector & LocalTangentX, FVector & LocalTangentY, FVector & LocalTangentZ, const [TArray](API\Runtime\Core\Containers\TArray)< [FColor](API\Runtime\Core\Math\FColor) > & HeightAndNormals ) const